digital readout testers vs colour charts

PMac2

Member
Dec 20, 2018
6
New Zealand
Hi,

So I'm curious about digital readout testers such as the LaMotte ColorQ series vs the classic reagent testers like the Taylor 2006K and the new(ish) Australian brand that I was directed to from a previous post which ships to NZ, ClearChoiceLabs...

It seems on this forum that most (if not all) people prefer the classic colour testers, what's the reason for this, cost, reliability, accuracy, ease of use etc?
The digital readouts give easy to read numbers like pH 7.4 which one would hope were accurate whereas the classics require colour matching on a chart? Surely the singular digital number is easier to interpret?
I'm not colour blind (yet) that I know of and admittedly using a very basic model at the moment, Aussie Gold 4 in1, but I find it pretty hard to read it accurately along with the litmus tests due to the large range between colours on the chart. I haven't seen the Taylor or ClearChoice comparison charts in person so guessing they possibly come in smaller incremental matching between colours or I just need to refine my eye somewhat?

Ps.......Actually I did only buy the Aussie Gold 3 weeks ago and took it back today because the alkalinity was showing 160 (16 drops of solution 3 to turn clear or slightly yellow) and the litmus was showing what I determined to be approx 100ish. The pool shop SpinTouch confirmed Alk at 106 and tested the AG themselves (they sold it to me) but were at a loss to explain why it's so far out. The side of the bottle says "Lotq 02 17" which we all assumed was either the packing or manufacture date and not the expiry date.....

Excuse my ranting and drawn out ramblings...it's just how I am...but love to hear thoughts/reasons for reagents over digital.
Also I know the digital readouts use reagents, just simplifying for the discussion.

Cheers
Phil
 

AUSpool

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Geday Phil and welcome to the forum,

As you may have guessed from Allen’s post above the test kit debate is a common topic. One of the corner stones of TFPC is a reliable test kit that users can get repeatable results at home and forum members can see results that they are confident re accuracy to offer advice. To this end it is the drop tests, the TF100 or Taylor K2006 that offer the best reliability, ease of use and repeatable results for home use. The FAS-DPD chlorine test is the best there is, it is a titrating drop test with a definite and defined end point and capable of reading accurately to 20ppm. In comparison the colourQ uses a colour metric test with an optical reader that can only read to 10ppm and has more elements for the introduction of error.

There is essentially three types of tests, a titration test which has a definite end point, colour metric tests such as the pH test, or the turbidity test as used for cyanuric acid (CYA). The colourQ and the SpinTouch are both LaMotte products that use colour metric tests with optical readers. The stores SpinTouch computer system will adjust total alkalinity (TA) by the amount of (CYA) it thinks you have. We like to test for calcium hardness (CH) and while the colourQ and SpinTouch say they test for CH they actually test total hardness which includes magnesium. This can be particularly problematic if you actively add magnesium salts.

The TF100 doesn’t ship to AUS or NZ which is why a lot of us use Clear Choice Lab products. You can get the Taylor K2006 and Speedstir shipped from http://www.poolvacparts.com/
 

CaveDiver1932

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Mar 2, 2014
110
Dallas
Don’t recall any of those reviews stating they calibrated the lamotte. That’s kinda an important detail left out of those threads. Begs the question about the other proper use of the machine as well.

I have heard early next year Lomotte is releasing an updated Q model.
 

AUSpool

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I forgot to mention the electrical potential meters such as pH pens, salt meters and TDS meters. These use the electrical potential of a fluid and then apply a best guess conversion factor. These range from cheep and cheerful to very expensive where the more expensive ones should be more accurate. All are only as good as the last calibration and choice of calibration point. As with any test all have accuracy ranges but often the electrical testers, ColourQ and SpinTouch offer results with too many decimal places giving the illusion of accuracy. - such as your SpinTouch result of 107ppm - I would call it 110ppm.

NB: Your alkalinity test at 160ppm is probably on the money. If I call the SpinTouch test 110ppm, add a bit for accuracy and add back your CYA level which they may have deducted without telling you or even knowing themselves. If I take a stab in the dark and pick 40 - 50ppm CYA then we’re at 150 - 160ppm TA which is on the money given that that Aussie gold test would have a ~10% accuracy at that level.
 

AUSpool

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Don’t recall any of those reviews stating they calibrated the lamotte. That’s kinda an important detail left out of those threads. Begs the question about the other proper use of the machine as well.

I have heard early next year Lomotte is releasing an updated Q model.

Your absolutely right. The ColourQ can not be calibrated by the end user. When my ColourQ was near the end of its useful life I was able to have it sent back and have it factory re calibrated, checked for serviceability and shipped back with new vials at a cost. The SpinTouch devices have an online calibration function and I have no idea how that works.

I’ll stick with my K2006 and Speedstir. ;)
 

Jezza

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Good info and summary Auspool.

For the regular TFP user- the TF-100, K-2006C or the kit from Clearchoice Labs are accurate, reliable and with a bit of practice easy to use. I think one of the often under-rated benefits of having your own test kit is no more having to head out to get dodgy pool store test results while going through the hassle of brushing off the staff with the sales pitch to buy all sorts of pool chemicals.

FWIW- There are also several You tube clips on how to perform each of the tests using the Taylor test kit to give you an idea of what is involved.
 

PMac2

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Dec 20, 2018
6
New Zealand
NB: Your alkalinity test at 160ppm is probably on the money. If I call the SpinTouch test 110ppm, add a bit for accuracy and add back your CYA level which they may have deducted without telling you or even knowing themselves. If I take a stab in the dark and pick 40 - 50ppm CYA then we’re at 150 - 160ppm TA which is on the money given that that Aussie gold test would have a ~10% accuracy at that level.

Interesting....and here I was thinking the 4in1 AG would be the one causing the issue.....my cya is at approx 130ppm (after dumping 75% to get it down), well according to 2 x Spintouch tests from different stores it is.
 

AUSpool

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Interesting....and here I was thinking the 4in1 AG would be the one causing the issue.....my cya is at approx 130ppm (after dumping 75% to get it down), well according to 2 x Spintouch tests from different stores it is.

As I recall the formula shops use for adjusting TA is TA -1/3CYA. If the SpinTouch got 110ppm for adjusted alkalinity and 130ppm CYA then reversing the adjusting would give you 110 + (1/3 130) = 154ppm TA. Add a bit for accuracy and your on the money at 160ppm with the 4in1. I’d be getting that 4in1 back. If your CYA is 130ppm you need to get it down bellow 90ppm for your chlorine to be effective. And I would be working on lowering your TA to ~70ppm.
 

PMac2

Member
Dec 20, 2018
6
New Zealand
Thanks AUSpool......my brain hurts thinking about all of this...

So not only is there a correlation between cya and fc but now TA as well....I need some definitive reading to outline it all!!

Why do you say get the TA down to 70? I know the chart says 70-90+ and what I can't work out is 90+ is such an arbitrary number so clearly based upon other chem levels?

Ps...I bought a CCL kit and it's on the way.
 

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ajw22

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CYA and FC work together and are related.

PH and TA are related.

TFPC methods don’t use “adjusted TA”. If you use our methods you don’t have to understand it. Other methods introduce more complexity to understand.

Lowering TA will reduce the rate of your PH rise. TA will come down naturally as you add MA to reduce PH.

The basics you need to understand for TFPC methods are at Pool School - ABCs of Pool Water Chemistry
 

EminiTrader

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I don't generally comment on these threads... but I own a Spin Touch, ColorQ, and I use the Taylor. When my pool first opened (september 2018) I used all 3 for nearly the entire year. My results are almost NEVER the same but ALWAYS within a few percentage points. Awhile ago I read here that you can buy water from TFTtestkits that are already "balanced" - a good way to test. I ordered the small bottles here and I ordered the large bottles from Taylor - the results we're about the same - always within a few percentage points.

I understand that the Taylor is by far the best. I know. I use it. But many here believe the spin touch and/or colorq are just simply inaccurate. I disagree for the reasons above. As a color blind person having options I know are accurate (or close enough) works for me. Generally, however, I use the Taylor and have family help me with PH - the others I can pretty much tell.
 

dschlic1

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With the TFT kits, the CYA and pH do not have a definite endpoint. For the CYA test, the disappearing dot is should still be slightly visible at the correct reading. There was a thread or two on this a few years ago. Many people, including me, were reading the CYA levels as too high. First big source of difference between colorimeters and the "drop" tests. I have always found the the colors on the pH test do not match up very well to the chart. If I add more drops of the pH test solution, I find the colors get closer, but never a definite match.
 

tomfrh

Well-known member
Jan 30, 2018
489
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My pool shop uses the digital one. He says it’s “a thousand times more accurate” than my home testing.

- - - Updated - - -

OP, I use clear choice labs kit, and Aussie gold 4 in 1. I prefer the Aussie gold for ph. The water column is taller and allows side by side comparison of every colour square.
 

AUSpool

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My pool shop uses the digital one. He says it’s “a thousand times more accurate” than my home testing.

- - - Updated - - -

OP, I use clear choice labs kit, and Aussie gold 4 in 1. I prefer the Aussie gold for ph. The water column is taller and allows side by side comparison of every colour square.

And unfortunately thats he kind of comment that we’ve come to expect from pool shops, from the manufacture’s own reported accuracy values at best they are close to equal but still have limitations. In reality I have found the opposite, over the years Ive found the pool shop tests to be out by as much as 15% particularly with salt, pH and CH. A couple of the shops have been out by as much as 1000ppm simply because they do not know how to use their equipment properly.

I prefer the Aussie gold pH comparator to the one that came with my K2006, is seems easier to compare for me.
 

AUSpool

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I don't generally comment on these threads... but I own a Spin Touch, ColorQ, and I use the Taylor. When my pool first opened (september 2018) I used all 3 for nearly the entire year. My results are almost NEVER the same but ALWAYS within a few percentage points. Awhile ago I read here that you can buy water from TFTtestkits that are already "balanced" - a good way to test. I ordered the small bottles here and I ordered the large bottles from Taylor - the results we're about the same - always within a few percentage points.

I understand that the Taylor is by far the best. I know. I use it. But many here believe the spin touch and/or colorq are just simply inaccurate. I disagree for the reasons above. As a color blind person having options I know are accurate (or close enough) works for me. Generally, however, I use the Taylor and have family help me with PH - the others I can pretty much tell.

I don’t disagree. The SpinTouch is an expensive meter for home use, I guess one draw back is it is a bit of a waste of an entire disc if you only want to check FC. If you only want to check single perameter use you ColorQ or the Taylor.

I used the ColorQ for a few years and found the results quite good. The robustness of the kit is an issue though, I have had formal lab training and was very careful with its use but if I gave it to a mate to be used he would wreck it in a week.
 

AUSpool

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Back to the OP, I don’t think I answered the question properly and have added an element of confusion or misunderstanding so going back to the initial question;
...

It seems on this forum that most (if not all) people prefer the classic colour testers, what's the reason for this, cost, reliability, accuracy, ease of use etc?
The digital readouts give easy to read numbers like pH 7.4 which one would hope were accurate whereas the classics require colour matching on a chart? Surely the singular digital number is easier to interpret?
...

In essence your asking why do most users prefer the pH colormetric test over an electronic pH meter? If properly used and calibrated a pH meter can be accurate and easy to read but are expensive and take a bit of effort for very accurate results. The average pool owner wont have access to a quality meter or bother with calibrating it before each use were the colormetric tests are cheep, easy to use and with a bit of practise are accurate enough with repeatable results.

Most users here prefer the TF-100 or the Taylor K2006 kits which use a colour metric test for pH, a turbidity test for CYA and titration tests for FC, CC, TA and CH. They are robust, easy to use, the accuracy is good and the results are repeatable for greatest amount of users.

I think of ‘the classic colour testers’ as what I would describe as a ‘colour metric tests’ were you apply several chemical compounds (liquid or solid) to a sample and you get a resulting solution with a colour that is directly related to a specific concentration. The coloured sample is then compared to a colour chart to get a final answer.

The digital readout meters such pH meters or TDS meters measure electrical potential and apply a conversion factor or as with pH meters the electrical potential is compared to a reference probe. Digital meters such as the ColorQ or SpinTouch are photo optical meters or photometers that use the traditional color metric chemistry and measure the light that passes through the sample and apply a conversion factor for a final readout.

The test that I most prefer is a titration test or ‘drop test’ that uses a colour sensitive dye and a titrating agent that gives a definate colour change or end point at the corresponding measured value.

A turbidity test is used for CYA where the value of CYA in he treated sample is directly related to how ‘see through’ it is.

The Aussie 4in1 uses colormetric tests for FC and pH, and titration ‘drop tests’ for TA and CH. I prefer the comparator that comes with the Aussie 4in1 to the one that came in my K2006. The tests that we can get from Clear Choice Labs are similar to those in the TF-100 or K2006. The TF-100 is not available to Australia or NZ, the K2006 is hard to get and expensive for shipping.

The digital meters often give answers that are too precise and not directly related to the meters reported accuracy. All tests have reported accuracy values and its important not to read to much into it, the reported values have the greatest potential or probability to be in the middle of range or closest to the reported value. But often the reported value is too precise such as your alkalinity at 106ppm, I would round up to 110ppm.

The ColorQ measures general hardness and not calcium hardness, it does not pre treat the sample to neutralise magnesium ions. We don’t bother with magnesium as it is way to soluble to cause issues in a swimming pool.

 
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alexsmith1

Active member
Oct 11, 2018
33
Gold Coast, Australia
As I recall the formula shops use for adjusting TA is TA -1/3CYA. If the SpinTouch got 110ppm for adjusted alkalinity and 130ppm CYA then reversing the adjusting would give you 110 + (1/3 130) = 154ppm TA. Add a bit for accuracy and your on the money at 160ppm with the 4in1. I’d be getting that 4in1 back. If your CYA is 130ppm you need to get it down bellow 90ppm for your chlorine to be effective. And I would be working on lowering your TA to ~70ppm.


Interesting.. I've had 2x Aussie Gold kits (lot Q 09 17) and the TA is way of like PMan2 results. My Water Technix kit is comparable to the pool shops SpinTouch results. The shop reports TA & Adjusted separately.
 

johnmw1

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Oct 7, 2015
70
Adelaide, Australia
I'm currently using a "Blue Devil" kit. Is this similar to the Aussie Gold kit do you think? I'm planning on buying a complete kit from CCL, but have seen comments that they prefer the Aussie Gold for PH testing. My biggest issue which I have mentioned before elsewhere is that I'm colourblind.

Cheers,
John
 

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